Technical staff from the animal disease prevention and control center inject chickens with the H5N1 bird flu vaccine in Shangsi county, Guangxi Zhuang autonomous region Wednesday.
Photo: Reuters.

China said it was mobilizing resources nationwide to combat a new strain of deadly bird flu that has killed four people, as Japan and Hong Kong stepped up vigilance against the virus and Vietnam banned imports of Chinese poultry.

The H7N9 bird flu strain does not appear to be transmitted from human to human, but authorities in Hong Kong yesterday raised a preliminary alert and said they were taking precautions at the airport.